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The Exorcist Code
The Exorcist Code
A diabolical killer is hunting exorcists.
Only the Vatican’s secret weapon can stop him—
if it doesn’t destroy them first.
From the bestselling author of The Paranormalist series comes a terrifying new tale of demonic possession and supernatural horror.
Father Callum is the Vatican’s most seasoned exorcist, a battle-hardened veteran of Hell’s worst horrors. But when his mentor is brutally murdered, Callum is forced to partner with Michael, an exorcist like no immune to possession, beyond corruption, and created for one purpose—destroying evil.
Their hunt leads them to a remote Italian village, where the Thompson family’s new home has become a battleground of the damned. Their teenage daughter is under siege, her body and soul twisted by a force beyond comprehension. But this is no ordinary demon.
The malevolent entity stalking them is evolving—growing stronger with each encounter. It has already begun rewriting the rules of possession and claiming new, terrifying abilities. If the two seasoned demonologists fail, the balance of good and evil may be shattered forever.
Echoing the dread of The Exorcist and The Omen and the supernatural tension of The Conjuring and The Amityville Horror, The Exorcist Code is a pulse-pounding psychological horror thriller perfect for fans of demonic mysteries, haunted house ghost suspense, and exorcism horror.
The Vatican’s greatest exorcist isn’t what he seems. But he may be their only hope against the Devil.
Only the Vatican’s secret weapon can stop him—
if it doesn’t destroy them first.
From the bestselling author of The Paranormalist series comes a terrifying new tale of demonic possession and supernatural horror.
Father Callum is the Vatican’s most seasoned exorcist, a battle-hardened veteran of Hell’s worst horrors. But when his mentor is brutally murdered, Callum is forced to partner with Michael, an exorcist like no immune to possession, beyond corruption, and created for one purpose—destroying evil.
Their hunt leads them to a remote Italian village, where the Thompson family’s new home has become a battleground of the damned. Their teenage daughter is under siege, her body and soul twisted by a force beyond comprehension. But this is no ordinary demon.
The malevolent entity stalking them is evolving—growing stronger with each encounter. It has already begun rewriting the rules of possession and claiming new, terrifying abilities. If the two seasoned demonologists fail, the balance of good and evil may be shattered forever.
Echoing the dread of The Exorcist and The Omen and the supernatural tension of The Conjuring and The Amityville Horror, The Exorcist Code is a pulse-pounding psychological horror thriller perfect for fans of demonic mysteries, haunted house ghost suspense, and exorcism horror.
The Vatican’s greatest exorcist isn’t what he seems. But he may be their only hope against the Devil.
- GenresHorrorParanormal
234 pages, Paperback
First published March 17, 2025
236 people are currently reading
125 people want to read
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Displaying 1 - 30 of 41 reviews
March 25, 2025
What Lies In Store For Exorcist Priests?
Small backstory:
Father Callum, a renowned exorcist priest has been partnered with an unusual young priest (Michael) that seems to have veteran capabilities of being an exorcist that can withstand any type of demonic warfare.
The Vatican has created Michael behind closed doors to be able to deal with any type of demonic force and is immune to possession. Father Callum is wary and skeptical of what Michael can really do in the forces of battle so he will need to test his abilities in true form, but the question remains, will the Vatican regret their decision of creating Michael for such a purpose?
That is about all I can hand out with a small backstory so if you want to know more then go read this book!
Thoughts:
This book starts out with a bang and doesn't let up throughout the whole story! The author, William Massa pulled me straight into the story and kept the pedal to the metal down all the way to the end of the book!
I was only planning on reading just a few chapters as this book is steeped heavy into the occult and demons as it is wrapped around exorcist priests and possession but I ended up reading more than a few chapters as I stayed up to the early hours of the morning with reading over 70% of the book as I just could not put it down! Another great book by this author as I have read a few of his books in the past including two complete series! Looking forward to reading more books by this author in the future. Giving this book five "Demonic Danger" stars!
Highly Recommend!
Small backstory:
Father Callum, a renowned exorcist priest has been partnered with an unusual young priest (Michael) that seems to have veteran capabilities of being an exorcist that can withstand any type of demonic warfare.
The Vatican has created Michael behind closed doors to be able to deal with any type of demonic force and is immune to possession. Father Callum is wary and skeptical of what Michael can really do in the forces of battle so he will need to test his abilities in true form, but the question remains, will the Vatican regret their decision of creating Michael for such a purpose?
That is about all I can hand out with a small backstory so if you want to know more then go read this book!
Thoughts:
This book starts out with a bang and doesn't let up throughout the whole story! The author, William Massa pulled me straight into the story and kept the pedal to the metal down all the way to the end of the book!
I was only planning on reading just a few chapters as this book is steeped heavy into the occult and demons as it is wrapped around exorcist priests and possession but I ended up reading more than a few chapters as I stayed up to the early hours of the morning with reading over 70% of the book as I just could not put it down! Another great book by this author as I have read a few of his books in the past including two complete series! Looking forward to reading more books by this author in the future. Giving this book five "Demonic Danger" stars!
Highly Recommend!
May 7, 2025
I was honestly disappointed with this one. it started off great with what you'd expect for an exorcist book, then came Michael and I was thrown off by the idea of a robot in the mix, but thought it was creative so I was curious.
It felt really rushed, the possession of Anne and Rachel I get was just to take over Michael, but I felt like it really flew through. Even at the Vatican it seemed so rushed - chaos then Callum steps in and the exorcism was just done with not much action. The characters fell flat for me, there was really no build up or personality for Callum, I actually liked Michael the most who wasn't even human. I ended up liking the concept and potentional but it just wasn't there for me.
It felt really rushed, the possession of Anne and Rachel I get was just to take over Michael, but I felt like it really flew through. Even at the Vatican it seemed so rushed - chaos then Callum steps in and the exorcism was just done with not much action. The characters fell flat for me, there was really no build up or personality for Callum, I actually liked Michael the most who wasn't even human. I ended up liking the concept and potentional but it just wasn't there for me.
This entire review has been hidden because of spoilers.
January 8, 2026
Very unique premise! I enjoyed this one quite a bit, and will be looking out for the next.
March 25, 2025
Loved it
I really enjoy reading about religion and exorcism. Very entertaining. I read this book in one afternoon, couldn't put it down. Would sure like a second book.
I really enjoy reading about religion and exorcism. Very entertaining. I read this book in one afternoon, couldn't put it down. Would sure like a second book.
March 25, 2025
“Someone’s playing hard to get“
When a demonic serial killer possesses the innocent as bait in order to kill exorcists, a spiritual warfare-weary priest discovers the Vatican’s plan to enhance their work through artificial intelligence and technology. After all, faith, and science can work together, right? Of course, things go terribly wrong precisely at a time when prayers don’t seem to be enough. William Massa’s expertise in writing horror and science fiction come together in this masterful, supernatural techno thriller. The lead characters are well developed, the action is relentless, and the horror goes beyond the typical exorcism-related tropes. I found it impossible to put this book down.
When a demonic serial killer possesses the innocent as bait in order to kill exorcists, a spiritual warfare-weary priest discovers the Vatican’s plan to enhance their work through artificial intelligence and technology. After all, faith, and science can work together, right? Of course, things go terribly wrong precisely at a time when prayers don’t seem to be enough. William Massa’s expertise in writing horror and science fiction come together in this masterful, supernatural techno thriller. The lead characters are well developed, the action is relentless, and the horror goes beyond the typical exorcism-related tropes. I found it impossible to put this book down.
March 25, 2025
Exciting From Beginning to End
I've been a fan of Mr Massa for several years. His writing drives the reader forward with a fury. The Exorcist Code is no exception. No spoilers, so I will just say the concept is ingenious and the story flies by. Fr Callum is deep and fleshed out but there is more to learn about his past. I'm looking forward to it.
I've been a fan of Mr Massa for several years. His writing drives the reader forward with a fury. The Exorcist Code is no exception. No spoilers, so I will just say the concept is ingenious and the story flies by. Fr Callum is deep and fleshed out but there is more to learn about his past. I'm looking forward to it.
March 26, 2025
A new code
In the age old struggle between good and evil the names may change, but the goal will always be the same banish the evil from where it came . The fathers put up a great fight but evil doesn't play fair Hopefully Father Calling will be continuing on this fight in future books
In the age old struggle between good and evil the names may change, but the goal will always be the same banish the evil from where it came . The fathers put up a great fight but evil doesn't play fair Hopefully Father Calling will be continuing on this fight in future books
March 26, 2025
The next step
With the advent of technology, new avenues of horror arise. For a novella, this story read like a screenplay and I could envision it as if i was watching tv instead of reading a story. Scary good.
With the advent of technology, new avenues of horror arise. For a novella, this story read like a screenplay and I could envision it as if i was watching tv instead of reading a story. Scary good.
October 23, 2025
This story surprised me with creative twists multiple times. It would make a good scary movie and like someone else said, I’d love a second book! This is currently free to listen to on audible though it’s with an AI voice that isn’t the most pleasant. That kind of made sense for this book though.
April 21, 2025
being a horror lover, I am always looking for something that will hold my attention from the get go and keep it throughout. this book certainly did that and then some. it was so incredibly detailed that I felt I was standing in the room during the exorcisms. Well done sir well done! Now on to Fear the Light!
May 9, 2025
An excellent book..makes you think about why AI should only be used in a limited manner
June 20, 2025
Robot-demon is not something I expected to encounter.
This entire review has been hidden because of spoilers.
May 24, 2025
The Exorcist Code
by William Massa
Publication date: March 24, 2025
236 Pages
Star Rating: ⭐⭐⭐⭐⭐
Dread Factor: 💀💀💀
Trigger Warnings: Demonic possession, child endangerment, spiritual warfare, Vatican-level conspiracy vibes
What Did I Just Walk Into?
So apparently, the Vatican decided the best way to deal with an exorcist-murdering demon was to build a Terminator-priest named Michael. Because nothing says “holy protection” like an AI with a crucifix. And honestly? I’m here for it.
Father Callum—grizzled, faith-torn, probably on his tenth cup of holy espresso—teams up with Michael, the Vatican’s shiny new exorcism toy, to hunt down this demon that’s playing 4D chess with the rules of possession. Meanwhile, in the middle of an Italian village, a poor teenage girl’s stuck as demon bait because that’s how this universe apparently rolls.
Here’s What Slapped
📖 The whole Terminator meets The Exorcist vibe? Chef’s kiss.
📖 Michael’s unflappable AI logic paired with Father Callum’s human doubt—talk about a buddy cop team-up from the depths of Hell.
📖 The demon isn’t your run-of-the-mill bad guy. It’s evolving, and let me tell you, nothing gets my horror-loving heart going like a demon with a learning curve.
📖 Action sequences that feel like a horror movie on fast forward—intense, creepy, and bloody as hell (literally).
What Could’ve Been Better
📖 Callum, buddy, maybe stop second-guessing your team-up with the Vatican robot in the middle of an exorcism.
📖 Michael, I love you, but you could use a little more personality. Even AI needs a hobby, okay?🤪
📖 Perfect for Readers Who Love:
📖 Demonic horror that doesn’t stick to the script
📖 Vatican conspiracy horror with a sci-fi twist
📖 Faith, firepower, and enough existential dread to keep you up at night
📖 That delicious tension of “can you even trust the good guys?”
Reviewed by Robin’s Review
by William Massa
Publication date: March 24, 2025
236 Pages
Star Rating: ⭐⭐⭐⭐⭐
Dread Factor: 💀💀💀
Trigger Warnings: Demonic possession, child endangerment, spiritual warfare, Vatican-level conspiracy vibes
What Did I Just Walk Into?
So apparently, the Vatican decided the best way to deal with an exorcist-murdering demon was to build a Terminator-priest named Michael. Because nothing says “holy protection” like an AI with a crucifix. And honestly? I’m here for it.
Father Callum—grizzled, faith-torn, probably on his tenth cup of holy espresso—teams up with Michael, the Vatican’s shiny new exorcism toy, to hunt down this demon that’s playing 4D chess with the rules of possession. Meanwhile, in the middle of an Italian village, a poor teenage girl’s stuck as demon bait because that’s how this universe apparently rolls.
Here’s What Slapped
📖 The whole Terminator meets The Exorcist vibe? Chef’s kiss.
📖 Michael’s unflappable AI logic paired with Father Callum’s human doubt—talk about a buddy cop team-up from the depths of Hell.
📖 The demon isn’t your run-of-the-mill bad guy. It’s evolving, and let me tell you, nothing gets my horror-loving heart going like a demon with a learning curve.
📖 Action sequences that feel like a horror movie on fast forward—intense, creepy, and bloody as hell (literally).
What Could’ve Been Better
📖 Callum, buddy, maybe stop second-guessing your team-up with the Vatican robot in the middle of an exorcism.
📖 Michael, I love you, but you could use a little more personality. Even AI needs a hobby, okay?🤪
📖 Perfect for Readers Who Love:
📖 Demonic horror that doesn’t stick to the script
📖 Vatican conspiracy horror with a sci-fi twist
📖 Faith, firepower, and enough existential dread to keep you up at night
📖 That delicious tension of “can you even trust the good guys?”
Reviewed by Robin’s Review
April 4, 2025
I almost removed the book from my Scribe when it was unveiled that Michael was an AI. After finishing the book, I wish I would have indeed removed it.
A veteran exorcist given an introduction that speaks of his unwavering faith, yet has multiple instances of having his feelings hurt during his attempts to exorcize a single demon.
A demon with absolutely no connection to demon/devil lore, speaks of being on the lower rungs of Hell's hierarchy, yet manages to cause more strife than Satan would himself.
A demon deemed "ancient" multiple times, seems to suddenly get a doctoral degree in cybersecurity, during his off-time from possessing people, making the kids in the movie Hackers look like nothing more than 'script kiddies'.
Demon is foiled in a very underwhelming way, yet a mere year later is hastily climbing up the ranks in the Vatican itself.
I could go on, but would rather this book fade from memory.
A veteran exorcist given an introduction that speaks of his unwavering faith, yet has multiple instances of having his feelings hurt during his attempts to exorcize a single demon.
A demon with absolutely no connection to demon/devil lore, speaks of being on the lower rungs of Hell's hierarchy, yet manages to cause more strife than Satan would himself.
A demon deemed "ancient" multiple times, seems to suddenly get a doctoral degree in cybersecurity, during his off-time from possessing people, making the kids in the movie Hackers look like nothing more than 'script kiddies'.
Demon is foiled in a very underwhelming way, yet a mere year later is hastily climbing up the ranks in the Vatican itself.
I could go on, but would rather this book fade from memory.
March 27, 2025
The Vatican has assigned Father Callum and Michael to eliminate a malevolent entity behind a string of brutal exorcist murders sweeping Europe. The two exorcists arrive at an isolated Italian village where the Thompsons’ new residence has become a scene of a fierce conflict. A frightening presence is physically and spiritually attacking their teenage daughter.
With each confrontation, the evil being becomes more powerful and redefines possession, which results in this horror story becoming more terrifying. While I am not a fan of science fiction, Mr. Massa has cleverly combined the sci-fi and horror in such a way that I did not see the twists coming. I highly recommend this frightening new story.
With each confrontation, the evil being becomes more powerful and redefines possession, which results in this horror story becoming more terrifying. While I am not a fan of science fiction, Mr. Massa has cleverly combined the sci-fi and horror in such a way that I did not see the twists coming. I highly recommend this frightening new story.
May 7, 2025
An interesting story line, but it seemed a bit rushed. For me, this affects the depth of character development as well as the finished product. I can envision this concept going to a movie script, but the movie would need more substance than the book it sprang from, and that rarely happens.
If you’re a reader that enjoys a quick resolution and turn-around, this book might be for you. Conversely, if you like to ‘care’ about the characters in your readings, you may not find that possible in this work. I might try one more from this author, since I’m curious about a character from another work dubbed “Akasha”. If I give it a read, I’ll review it as well. In summary, for me it seemed a shallow read, but with a novel concept and near-endless possibility.
If you’re a reader that enjoys a quick resolution and turn-around, this book might be for you. Conversely, if you like to ‘care’ about the characters in your readings, you may not find that possible in this work. I might try one more from this author, since I’m curious about a character from another work dubbed “Akasha”. If I give it a read, I’ll review it as well. In summary, for me it seemed a shallow read, but with a novel concept and near-endless possibility.
June 25, 2025
I think this book is going to be a love it or leave type affair. Overall it wasn't bad read but there are two caveats to work through.
The first is just the general rushed nature of the story and how it develops. The story is pretty blunt and in your face with all the exorcism tropes of trying to ignore the demon and overcoming self doubt. The big action scenes happen quickly and are almost anticlimactic.
The second caveat is where the love or hate comes into play. The rookie exorcist is an android. The author is clearly trying to blend modern tech with a classic storyline. For me it just didn't sit well. If that convention works for you then you'll undoubtedly enjoy this book more than I did.
The first is just the general rushed nature of the story and how it develops. The story is pretty blunt and in your face with all the exorcism tropes of trying to ignore the demon and overcoming self doubt. The big action scenes happen quickly and are almost anticlimactic.
The second caveat is where the love or hate comes into play. The rookie exorcist is an android. The author is clearly trying to blend modern tech with a classic storyline. For me it just didn't sit well. If that convention works for you then you'll undoubtedly enjoy this book more than I did.
This entire review has been hidden because of spoilers.
March 26, 2025
I have read a lot of this authors books and for the most part liked them, this one was a exception. ***Possible Spoilers*** I downloaded this book by accident as this is not the type of book I usually read however I thought I would give it a go, it started out ok I liked how they named the exorcist robot after the archangel Micheal however I didn't particularly like how they made the human exorcist so for lack of a better word scary, You're supposed to be warriors of GOD ,I also didn't like how Michael was so easily possessed and why would the Vatican think that a robot couldn't become possessed?? Didn't make sense. I stopped reading at 69% and deleted from my kindle
May 3, 2025
An interesting idea for the role of an exorcist
The powers that be did it again...put their noses and technology where maybe just maybe it didn't belong. Now they have no idea that the demon is now a high raking member of their order!
Using technology to create Michael, a robot programmed to perform the ancient ritual of exorcism... He is filled with all the knowledge and tools he needs to send demons back to hell. He doesn't have a soul so he can't be possessed by a demon right? Think again
The powers that be did it again...put their noses and technology where maybe just maybe it didn't belong. Now they have no idea that the demon is now a high raking member of their order!
Using technology to create Michael, a robot programmed to perform the ancient ritual of exorcism... He is filled with all the knowledge and tools he needs to send demons back to hell. He doesn't have a soul so he can't be possessed by a demon right? Think again
May 6, 2025
Starts out like a traditional supernatural thriller—priests, demons, rituals—and then suddenly swerves into sci-fi insanity. it stops pretending to be grounded and goes full throttle: Complete with a Cyberpunk Jesus .
The book is easy, fast-paced read, maybe even a bit **rushed in places**, especially toward the end.
Honestly, I’m not sure if I finished this out of sheer morbid curiosity or a genuine need to see how far the story would go—but either way, I couldn’t look away. It’s absurd, bold, and completely unhinged....
The book is easy, fast-paced read, maybe even a bit **rushed in places**, especially toward the end.
Honestly, I’m not sure if I finished this out of sheer morbid curiosity or a genuine need to see how far the story would go—but either way, I couldn’t look away. It’s absurd, bold, and completely unhinged....
September 14, 2025
Strange Twist On Possession
Freaky quick read introducing robotic exorcists. Not generally my cup of tea but entertaining to say the least. What if the Catholic church decided to delve in technology to save priests from losing their lives trying to expel a demon from an innocent. Interesting indeed but to actually believe a machine has a soul? Not too sure on that one. Read I'm sure you won't be disappointed if you just open your mind a tad.
Freaky quick read introducing robotic exorcists. Not generally my cup of tea but entertaining to say the least. What if the Catholic church decided to delve in technology to save priests from losing their lives trying to expel a demon from an innocent. Interesting indeed but to actually believe a machine has a soul? Not too sure on that one. Read I'm sure you won't be disappointed if you just open your mind a tad.
January 13, 2026
Favorite quote: "Church leaders do make such creative sadists." I truly enjoyed this book. A nice blend of technology and faith with a dash of conspiracy. It is a great gateway into probing your own thoughts, beliefs and theories. I did appreciate the detail to imagery. It allowed my mind to conjure the scenes and that in itself created so much fun. I look forward to the second book. I also, appreciated the emotional tug it gave. I wasn't expecting that.
November 8, 2025
As an avid horror movie fan, I found this book to be quite cinematic and easy to picture as I read it. I'm not typically a Sci-fi gal, but found the concept to be a fresh one I haven't heard before.
I definitely like this author's style and am interested if his other works follow suit. I especially love a book that uses short, consumable chapters to propel the reader through.
I definitely like this author's style and am interested if his other works follow suit. I especially love a book that uses short, consumable chapters to propel the reader through.
March 31, 2025
Outstanding
An unbelievable experience. The depth of this story is beyond what you would expect in any novel. The story blends all the elements of excellent, mixes in a dose of misdirection, and ends with a finish that is both satisfying and frightening.
An unbelievable experience. The depth of this story is beyond what you would expect in any novel. The story blends all the elements of excellent, mixes in a dose of misdirection, and ends with a finish that is both satisfying and frightening.
April 5, 2025
WOW
This is one of the best books I’ve read on exorcism!!! A fast read but you become immersed in the story from page 1. I hope this becomes a series. This is a MUST READ!!! Great job Mr. Massa.
This is one of the best books I’ve read on exorcism!!! A fast read but you become immersed in the story from page 1. I hope this becomes a series. This is a MUST READ!!! Great job Mr. Massa.
April 5, 2025
Father Callum is an exorcist for the Vatican, when a new dark power starts targeting exorcists. He is partnered up with a new kind of exorcist, an android, which is intended to turn the tide against the evil looking to take control.
April 15, 2025
The Exorcist Code
There comes a time when all religion and its nonsense of fake superstition finally comes to an end and mankind is destroyed and is surpassed by artificial intelligence and robots that will one day rule this world with cold hard logic
There comes a time when all religion and its nonsense of fake superstition finally comes to an end and mankind is destroyed and is surpassed by artificial intelligence and robots that will one day rule this world with cold hard logic
May 1, 2025
So many adjectives
Adjectives used to fill space. The story was convoluted at best. Spelling and grammar mistakes abound. No real character development. Jumps around too much.
I cannot believe people have rated this book higher than a 2.
Adjectives used to fill space. The story was convoluted at best. Spelling and grammar mistakes abound. No real character development. Jumps around too much.
I cannot believe people have rated this book higher than a 2.
July 14, 2025
Hooked from page one is an understatement!!!
I haven’t found a book in a long time that has hand me in its grips and wouldn’t let go like this one. The setting, the story, the twists and turns held my attention the whole time through. I can’t wait to read more from this author!!!
I haven’t found a book in a long time that has hand me in its grips and wouldn’t let go like this one. The setting, the story, the twists and turns held my attention the whole time through. I can’t wait to read more from this author!!!
July 28, 2025
Excellent read! Hard to put it down.
The pace was great from beginning to end. For those who like this sort of spiritual adventures, I highly recommended it. I will definitely follow the author!
The pace was great from beginning to end. For those who like this sort of spiritual adventures, I highly recommended it. I will definitely follow the author!
Displaying 1 - 30 of 41 reviews